The Voice Call Continuity (VCC) specification describes how a voice call can be maintained as a mobile device moves between a circuit switch network and a packet-switched network. Within a standard VoIP call, the operation of the mobile devices are controlled by the IP infrastructure. However, within the VCC specification, calls to and from a mobile device in the circuit switch domain are also anchored to the IP domain, for example, the IP Multimedia Subsystem (IMS). As the handset becomes attached and detached from wireless access points, such as Wi-Fi hotspots, a client application within the mobile device provides notification of the radio conditions through a VCC platform within the network. This enables circuit switched and IP switched call links to be originated and terminated in a transparent manner such that each path is automatically transferred between domains.
Current VCC solutions anchor all VoIP originated calls to the IMS VCC application server within the IMS network. This is irrespective of whether the VoIP calls eventually are handed down to another Radio Access Technology (RAT) such as eHRPD or 1xRTT. The need for always anchoring these calls within the IMS network results in higher licensing costs for use of the VCC application server.